An integrated conductive hydrogel triboelectric nanogenerator for digital monitoring of sports-related motions

Digital monitoring of competitive sports requires wearable sensors that are flexible, reliable, and self-powered. Herein, a poly(vinyl alcohol)/chitosan/reactive dye hydrogel, denoted as PCR hydrogel, is designed to construct a hydrogel-derived triboelectric nanogenerator, termed PCR-TENG, for athletic motion monitoring. In this device, the PCR hydrogel serves simultaneously as the triboelectric contact layer and flexible ionic electrode, while polytetrafluoroethylene acts as the counter triboelectric material. The hydrogel gains good flexibility, structural integrity, and stable conductivity under repeated deformation through the combined effects of PVA crystallization induced by freeze and thaw treatment, intermolecular interactions regulated by reactive dyes, ionic conduction, and water retention assisted by glycerol. The optimized PCR-TENG delivers an open-circuit voltage (VOC) of 193.8 V, a short-circuit current (ISC) of 23.4 μA, a transferred charge (QSC) of 89.1 nC, and a maximum output power of 0.87 mW. It also maintains stable outputs under varied frequency, force, displacement, humidity, temperature, and prolonged operation. As a wearable self-powered sensor, the PCR-TENG enables real-time monitoring of walking, running, jumping, boxing, and joint bending, offering a promising platform for self-powered biomechanical signal acquisition and wearable sports motion monitoring.